Morphological alterations of Saccharomyces cerevisiae induced by benanomicin A, an antifungal antibiotic with mannan affinity

Abstract

The effects of benanomicin A, a mannose-binding antifungal antibiotic, on yeast cells of Saccharomyces cerevisiae were studied by electron microscopy. Cytological studies using vital stain with methylene blue demonstrated that benanomicin A at 20 and 80 μg/ml killed buds in preference to parent cells. In confirmation, examination by TEM revealed that benanomicin A at 80 μg/ml damaged buds more severely than parent cells. The major effect on the ultrastructure was characterized by severe damage to the cell membrane. In addition, it caused expansion and vacuolation of the endoplasmic reticulum (ER), and partial fragmentation and disappearance of nuclear membranes. The membrane-disruptive activity of benanomicin A may be closely associated with its membrane affinity.